Tokyo, June 9, 2011 — Tokyo Electric Power Corp. admitted that more than one reactor at the Fukushima Daiichi nuclear power plant suffered a meltdown in the wake of the earthquake and tsunami that hit Japan in March.
TEPCO will report these latest findings to the U.N. International Atomic Energy Agency. Japan’s Nuclear and Industrial Safety Agency also increased its estimation of the radiation released into the atmosphere in the first six days of the disaster to 770,000 terabecquerels — more than double the earlier estimate of 370,000 terabecquerels.
TEPCO officials said reactor units 2 and 3 had lost enough water that the fuel rods inside the reactor vessels were exposed, which caused them to heat up enough to melt. Originally the company had only said that meltdowns occurred at reactor unit 1.
TEPCO also said that a treatment facility for removing radiation from water will begin operating June 15. The equipment, engineered by Areva, can reduce the level of radiation in water to 1/10,000th of its original level, and can treat up to 1,200 tons of water per day.
Since the nuclear disaster began, plant operators have used large quantities of water to cool damaged reactor cores and to keep spent fuel ponds from heating up too much. Some of this radioactive water has been pumped into the Pacific Ocean, raising the radioactivity level of seawater and prompting complaints from nearby countries such as South Korea.
The Japanese government’s report to the IAEA found that sufficient measures were not in place at the time of the earthquake and tsunami that struck March 11. This left the plant vulnerable to disaster and hampered plant operators’ ability to respond, according to the report.
The venting of radioactive gases, which were performed in the weeks after the tsunami hit, were not enough to prevent the hydrogen explosions that happened at several units, causing fires and damaging reactor buildings, according to the report.
The report also referenced organizational difficulties resulting from confusion over exactly which agency should have led which efforts in the days and weeks following the disaster. Japan’s regulatory system on nuclear plants did not specify which organization held what responsibility, thwarting a cohesive response to the disaster, the report said.
The report also found that the Japanese government was too slow in ranking the nuclear disaster as a Level 7 event on the he International Nuclear and Radiological Event Scale. This ranking, which rates the Fukushima disaster on the same level as Chernobyl, was first announced April 12.
The findings of the report will be analyzed by the IAEA in its meetings Vienna that will begin June 20. Japan’s final report to the IAEA will be compiled after a government investigative committee releases its results next year.